1. Field of the Invention
The present invention relates to a prediction system.
2. Discussion of the Background
Conventionally, industrial robots such as spot welders are arranged on production lines to engage in processing such as sheet-metal processing for automobiles. The spot welders are provided with welding guns to weld various portions of an automobile body. For this purpose, the welding guns need to be capable of three-dimensional movement such as reverse rotation and swing movement. This involves repeated twisting and bending of a welding cable coupled to the welding gun, which in turn causes accumulated wear over time resulting in disconnection. Thus, as equipment maintenance, it is necessary to replace the welding cable before the disconnection occurs.
In order to grasp the time to replace the welding cable, it is necessary to implement a continuous monitoring system. It is difficult or impossible, however, to find an internal disconnection merely by visually observing the exterior of the cable. In view of this, common practice is to continuously monitor the value of electric resistance of the cable so as to estimate the deterioration of the cable, that is, the level of disconnection. For example, Japanese Unexamined Patent Application Publication No. 1-262080 discloses a prediction system that continuously monitors the electric resistance of a cable so as to predict a breakage.